I had to choose between the Glock 19 and the M&P9c. The XD was eliminated in the shop because I found it too bulky for my taste.
The only negative about the Glock was its bad quality sights that would have needed upgrading adding $100 / $150 to the total cost.
The M&P ergos fit me better than the Glock's, it was cheaper and also had a S&W $50 rebate and 2 free mags at the time.
The Glock did not feel good in the shop but I rented both anyways because shooting a gun and holding it in the shop are two different things.
As far as shooting goes, I found both guns to be accurate and reliable. Both had very low recoil and were real easy and comfortable to shoot.
The Glock is slightly easier/faster to take apart then the M&P. I liked both equally and could have bought either without the slightest doubt/regret.
In the end the M&P's slightly better ergos (for me), dot sights and lower price won but you can't go wrong with either.
That's my unbiased 02... Had the Glock been cheaper and equiped with better sights I would be owning it instead of the M&P.